Question: $\left[\begin{array} {ccc} 8& 6& 9& -2\\ 8& -3& 7& 9\\ -1& -9& 5& 1\\ 2& 1& -9& 3\\ 1& -3& 8& -8 \end{array}\right]$ What are the dimensions of the matrix?
Explanation: The first dimension is the number of rows in the matrix. There are $5$ rows. The second dimension is the number of columns in the matrix. There are $4$ columns. In conclusion, the dimensions of the matrix are $5\times 4$.